If it's a scenario, then you can select the "All Visable" option before you start a game.
If you are making a cutscene or something, then use map revealers (you really don't need to reveal all of the map, just the parts that you want the player to see). However, I am not sure how you can do it like the way Mark Stoker did it with his cutscene scenario in Tamerlane: POD (the map isn't visable, just no fog of war).
http://www.scnnetwork.com/corners/stan
Nobody forced you to read that site, remember